Electrical plug and base



June 24, 1941. v W rr RE 2,247,006

ELECTRICAL PLUG AND BASE Filed March 11,- 1940 2 Sheets-Sheet 1 lnventor J. 3 7 George l-Lwhdmore June 24, 1941. WHlTMQE 2,247,006

ELECTRICAL PLUG AND BASE 2Sheets-Sheet 2 Filed March 11, 1940 Q m u m HTMH m r Patented June 24, 1941 ELECTRICAL PLUG AND BASE George H. Whitmore, Detroit, Mich. assignor of two-fifths to August F. Brandt, Detroit, Mich.

Application March 11, 1940, Serial No. 323,316

Claims.

This invention relates to improvements in electrical outlet plugs and bases.- I

An object of the invention is to providean electrical outlet plug and base affording a quicker and easier interconnection thereof than prior constructions, and lending itself particularly to an easy manipulation in absence of adequate light or when location of the parts requires reliance primarily on the sense of touch in making the connection.

Another object is to provide a plug and base so constructed that the usual contact prongs of the plug may be definitely guided and directed into proper engagement with the corresponding contacts of the base.

A further object is to provide a. base with means for rotatively guiding the prongs of a plug into proper contact-making position.

Further objects are to provide an electrical plug having locating means thereon additional to its prongs to facilitate proper engagement with a base, and employing said locating means as a provision additional to the prongs for frictionally retaining the plug in such engagement, and to also utilize the locating means to hold both prongs in proper position thereon should one of the prongs become loosened.

These and various other objects the invention attains by the construction hereinafter described and illustrated in the accompanying drawings, wherein:

Fig. l is a top view of one type of electrical outlet base exemplifying the invention.

Fig. 2 is an axial cross sectional view of the same, taken on the line 2-4 of Fig 1, and showing in dash lines a plug being guided toward proper registration with said base.

Fig. 3 is a substantially axial view of the base,

taken on the line 3-3 of Fig. 1.

Fig. 4 is an axial sectional view of the improved plug taken on the line 4-4 of Fig. 5.

Fig. 5 is a bottom view of such plug.

Fig. 6 is a perspective view of a locating pin which is a feature of the illustrated plug.

Fig. 7 is an elevational view in partial axial section of a screw type base constructed in accordance with the invention.

Fig. 8 is a perspective view showing the invention applied to an electric iron.

Fig. 9 is a side elevational view of a fitting attachable to said iron.

Fig. 10 is an end view of the fitting.

Fig. 11 is a sectional view of the fitting taken on the line ll--ii of Fig. 10.

Fig. 12 is a cross-sectional view of the fitting taken on the line I 2-i2 of Fig. 10.

In these views the reference character I designates an electrical outlet base formed of any material carrying the usual paired prongs l to engage the contacts 2. The base is formed with a dished end face 5 and with an axially disposed socket 8 opening centrally of such face to snugly receive an insulating locating pin 1 projecting centrally from the plug. Said pin is predeterminedly longer than the prongs between which it is disposed so that it may hold the prongs clear of the face 5 while being itself guided by said face into alignment with the socket 6.

An annular groove, 8, vertically coaxial with the base, opens in the face 5, its bottom forming a pair of opposed cams 9 of inverted V-shape. arcuately extending between the contacts 2. (See Figs. 1, 2, and 3.) When the locating pin has been registered with the socket 6, this assures registration of the prongs d with the grooves The sloping faces of said came serve to induce rotation of the plug and prongs to establish their proper engagement with the contacts, the latter being secured to the base therebeneath by screws ii and projecting upwardly into the groove between the cams. Exteriorly attached to the base at opposite sides thereof are brackets i2 by wh ch it may be fastened to a suitable support.

The locating pin i, as best appears in Fig. 6, is integrally provided at an end thereof with oppositely projecting attachment lugs it, formed with slots it through which the prongs 4 may project.

A pair of screws i5 engaging the lugs i3 secure the locating pin to the plug and also hold the prongs in place, being passed through attachment lugs i6 formed on the inner ends of the prongs and clamped between the lugs l3 and plug. Should one of said screws become loosened, the locating pin and its lugs i3 serve to retain the corresponding prong in proper operative position.

The modification shown in Fig. 7 comprises a threaded base i' embodying the same principles as the base first described. The base I is formed with a dished face 5' into which opens an annular groove 8' of diameter suited to receive the prongs of the plug 3 orof any more ordinary pronged electrical plug. Axially formed in the modified base is a socket 6' centrally opening in the face 5 and adapted to snugly receive thelocating pin 1 of the plug 3. The contacts 2' of the base are electrically connected respectively to the usual screw thread forming sleeve l8 embracing the base and to the usual terminal button l9 centrally carried by inner end of the base i'.

In inserting the prongs of the plug 3 into either base it is merely necessary to lightly press the locating pin against any point of the disked face 5 or 5 as exemplified in dash lines in Fig 3, said face definitely guiding the pin 1 into registration with the socket 6 or 6'. As the pin enters such socket, the prongs of the plug enter the groove 8 or 8 and contact the sloping cam faces 9 or 9', the plug being thus rotated to direct the prongs into engagement with contacts 2 or 2'.

Either described base is adapted to coact with any common electrical pronged plug, but the plug 3 herein described is obviously preferable, being more easily and quickly applied.

Disposal of the locating pin 1 between the prongs of the plug affords it considerable protection against breakage. A plug and base are held more securely in engagement than heretofore by the described construction since the locating pin offers a material frictional resistance to withdrawal from the socket.

In a further modification illustrated by Figs. 8-12, the invention is employed to connect an electrical appliance with a source of current. The appliance exemplified is an electric iron 20 equipped with the usual paired contact pins 2|, between which a locating pin 22 of insulating material projects from the appliance, slightly exceeding the contact pins in length. The cord 23 which delivers current to the iron is equipped with a terminal fitting 24 having the usual sockets 25 to receive the pins 2| and having the usual circuit terminals 26 associated with the inner portions of said sockets. Midway between the sockets 25 is formed a socket 21 to accommodate the cating pin 22. The three described sockets open in an end face 28 of the fittin'g 24, which face is dished toward its center at which the socket 21 opens. The outer ends of the sockets 25 are flared to form arcuate grooves 29, centered at the axis of the socket 21, and extending substantially to the lateral marginsof said dished face.

In applying the fitting 24 to the appliance 20, the operation is closely similar to that of intercom necting the plug and base first described. The locating pin 22 is first caused to engage the dished face 28 at any point thereof and a slight pressure applied to the fitting will cause it to slide laterally to a position registering the central socket 21 with said pin. As the locating pin enters the central socket the contact pins 2| will enter the arcuate grooves 29, and the flare or pitch of such grooves will shift the fitting rotatively about the locating pin to register the contact pins with the sockets 25. Continued pressure will then seat the locating pin snugly in the central socket and engage the contact pins with the circuit terminals 26. It is of course possible to enter the locating pin in the central socket without contacting the pins 2| with the dished end face of the fitting, but no difliculty will be found in so positioning the fitting initially that the contact pins will enter the grooves 29 as the locating pin enters its intended socket.

The preferred angle of pitch for the described dished faces is between and degrees, since a lesser angle does not achieve an adequately free relative sliding between locating pin and said face, and a sharper angle requires an undue projection of the locating pin beyond the prongs.

The described invention is applicable to any wall, floor, or ceiling electrical outlet base, or to such base of any utensil or appliance.

The term "prongs as employed in preceding description and appended claims involves no limitation as to cross-sectional shape or form of the elements thus designated. The term plug is used as inclusive of such fittings as are commonly termed caps, and the term base as inclusive of such a fitting as is commonly termed a receptacle.

The invention is presented as including all such changes and modifications as come within the scope of the following claims.

What I claim is:

1. An electrical connector comprising two fittings of insulating material, one having a pair of spaced similarly projecting prongs, and the other having a pair of sockets spaced to receive said prongs and paired contacts in such sockets-for 1o engagement by the prongs, and further having an annular groove intersected at diametrically opposed points by said sockets, such groove progressively decreasing in depth substantially from the sockets to points substantially midway between the sockets, whereby pressure applied through the prongs to the bottom of said groove tends to deflect the pronged fitting rotatively to guide the prongs into engagement with said contacts.

2. An electrical connector comprising two fittings of insulating material one having a locating pin projecting substantially centrally from an end face of the fitting and having a pair of contact prongs spaced from and at opposite sides of the pin and materially shorter than the pin, and the other having a substantially central socket for receiving and locating said pin and having paired sockets for receiving'said prongs and contacts in the paired sockets for engagement by the prongs, said sockets opening in a face of the socketed fitting and such face being inclined in a dished form substantially from the periphery of said face to the central socket to guide the pin into registration with the central socket, the dished face being annularly grooved. to rotatively guide the prongs into their sockets and the groove bottom being cammed to slope toward said sockets at an angle inducing relativerotation of the fittings responsive to pressure of the prongs against 40 the groove bottom.

3. An electrical fitting comprising a body formed by insulating material, a pair of spaced substantially parallel contact prongs mounted upon and projecting from said body, a locating pin formed of insulating material mounted upon said body substantially midway between the prongs and projecting substantially parallel to the prongs and materially exceeding the prongs in length,

said pin having a supporting base projecting 5'0" toward the prongs, and fasteners attaching the prongs to said body. and engaging said base to further attach the' locating pin to saidbody.

4. An electrical fittingas set forth in claim 3,

' to accommodate said prongs.

5. An electrical connector comprising two fittings of insulating material, one having a locating pin projecting substantially centrally from an end face of the fitting and having a pair of contact prongs at opposite sides of the pin and materially shorter than the pin, and the other having a substantially central socket for receiving and locating the pin and having paired sockets for receiving the prongs, and contacts in the paired sockets for engagement by the prongs',.said sockets opening at one end ofthe socketed fitting and such end having a face inclined in. a dished form substantially from the peripheryofsaid face to guide the pin toward the central socket, and camways in said end curved about the axis of said central socket and intersecting said paired sockets and progressively increased in depth toward the paired sockets.

' GEORGE H. WHI'I'MORE. 

